Duct



FIG. 1 is a top view of a duct showing my new ornamental design.

FIG. 2 is a side view thereof.

FIG. 3 is a perspective view thereof.

FIG. 4 is a back view thereof; and,

FIG. 5 is an enlarged cross sectional view taken on line 5—5 of FIG. 2. 

The ornamental design for a duct, as shown and described. 